Dual Purpose Measurements with Displacement Sensors
Abstract
In this paper we show a laboratory experience describing the possibility to build a sensor using a coil to measure small thicknesses of materials with the possibility of measuring temperature simultaneously, with the same built sensor. Its operation is based on the following facts: An electric current (a.c), flows through a coil and a magnetic field appears producing self-induction characterized by an electromotive force induced in the coil, when a conductive piece is situated in front of the coil. That permits us to obtain information about the distance between the coil and the conductive piece. When this separation thickness is changing, the magnetic field around the coil changes, because the self-induction coefficient (L) is also changing. Using resistance and impedance measurements (voltage in our case) in the coil, an expression has been obtained for the determination of the thickness of a non-conductive sheet placed between a metallic plate and the coil. Calibration measurements of resistance with temperature have been obtained. The thermodynamic analysis is also presented showing the equation of state of the system between the voltage, temperature and the thickness of the non-conductive sample. The linear thermal-expansion coefficient of the sample is also determined.References
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Smith, A. W., Wiedenbeck, M. L. (1959). Electrical measurements. McGraw-Hill Book Company, Inc.: New York.
Jefimenko, O. D. (1989). An Introduction to the Theory of Electric and Magnetic Fields. Electret Scientific Company, Star City.
Keszei, E. (2012). Chemical Thermodynamics. Springer: New York
Kosov. I. L. (1964). Electronic Measurement Techniques and Experiments. John E. Remich.
Reitz, J. R., Milford, F. J., Christy, R. W. (1979). Fundamentals of the Electromagnetic Theory. Addison-Wesley: New York.
Serway. R. A. (1996). Physics for Scientists and Engineers, 4th ed. Saunders, New York.
Smith, A. W., Wiedenbeck, M. L. (1959). Electrical measurements. McGraw-Hill Book Company, Inc.: New York.
Published
2020-09-12
How to Cite
ANDRIO, Andreu; DEL CASTILLO, Luis Felipe; COMPAÑ, Vicente.
Dual Purpose Measurements with Displacement Sensors.
European Journal of Physics Education, [S.l.], v. 11, n. 2, p. 24-34, sep. 2020.
ISSN 1309-7202.
Available at: <https://eu-journal.org/index.php/EJPE/article/view/279>. Date accessed: 23 apr. 2024.
doi: https://doi.org/10.20308/ejpe.v11i2.279.
Issue
Section
Classroom Physics
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